1. Field of the Invention
The present invention relates to electronics enclosures and, more specifically, to a compressible conductive gasket used in electromagnetic shielding of an enclosure.
2. Description of the Prior Art
Complex electronic circuits, especially those used in medical and military applications, can be susceptible to interference from ambient electromagnetic radiation, referred to as electromagnetic interference (EMI). EMI can lead to incorrect results and equipment failure. Also, certain regulatory bodies, such as the FCC, limit the level of EMI that electronics devices can emit.
One method of shielding circuits from EMI and limiting the amount of EMI emitted by electronic devices is to place the device in a conductive enclosure. Since electromagnetic radiation will not propagate through a conductor, the shielded enclosure acts as a barrier to EMI. However, many enclosures include access doors that do not provide a complete conductive seal along the door edges. A significant amount of EMI can pass through gaps along door edges. To limit EMI passing through such gaps, door edges may be fitted with conductive gaskets.
In use with highly sensitive circuits, the conductive gaskets can include inflatable bladders (either pneumatic or hydraulic) that run along the length of the gasket. The inflatable bladders are used to provide sufficient compression to the gasket. To secure an access door, a technician deflates the gasket, secures the door and then re-inflates the gasket, usually using a removable pump. Such gaskets have several disadvantages. For example, a leak may form if the gasket is damaged or degraded. Such a leak will bleed off pressure, compromising the shielding effectiveness of the gasket. Also, inflatable gaskets require technicians to have gasket pumps available to inflate the gaskets.
Therefore, there is a need for a conductive gasket that provides comprehensive shielding with a high level of compression.
There is also a need for a conductive gasket that will maintain its shielding, even when degraded.
There is also a need for a conductive gasket that may be expanded without requiring an external pump.